O'Fallon Weather in August

The climate in O'Fallon during August can be summarized as hot, humid and reasonably dry.

August is in the summer in O'Fallon and is typically the 2nd warmest month of the year. Daytime maximum temperatures average around a muggy 31°C (87°F), whilst at night 19°C (65°F) is normal.

On average August is the 5th driest month of the year in O'Fallon with around 78mm 3.1 inches of rain making it a reasonably dry time to visit. This rainfall is typically spread over 8 days, although this may vary considerably.

On the flip side this corresponds to an average of 9.5 hours of sunshine per day.

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in O'Fallon in August 2024.